1. Field
The present invention relates generally to wireless communication devices and systems and more specifically to reducing power consumption in wireless communication devices.
2. Background
Bluetooth is a wireless personal area network technology supporting wireless voice and data communication between different devices that are typically within ten meters of one another. A number of different devices can be Bluetooth-enabled, for example, cell phones, personal digital assistants or laptop computers. Each such device is equipped with Bluetooth components, including a receiver and transmitter, allowing it to communicate with other similarly equipped devices nearby without the use of cables or other physical connections.
As an example, a wireless code division multiple access (CDMA) cell phone can be Bluetooth-enabled, meaning that the cell phone would be able to communicate in both the CDMA network and the Bluetooth network. Such a Bluetooth-enabled CDMA cell phone would comprise both Bluetooth and CDMA components.
In Bluetooth-enabled devices, for example a Bluetooth-enabled CDMA cell phone (“phone”), the Bluetooth component assumes a standby mode when the device is not actively communicating with other Bluetooth-enabled devices, i.e. it is not participating in a Bluetooth network. While in standby mode, the Bluetooth component searches for other Bluetooth-enabled devices by periodically performing a wakeup process during which process it scans the surrounding environment for other Bluetooth-enabled devices. If the Bluetooth component encounters other Bluetooth-enabled devices during the scanning process and determines that a connection is needed, it can perform certain protocols in order to establish a short-range, wireless connection between the phone and such other devices. Otherwise, the scanning task is turned off until a next wakeup process. The standby cycle of waking-up, scanning and turning off repeats typically once, twice, or four times every 1.28 seconds for the duration of the standby period. However, it is appreciated that certain Bluetooth specifications may vary the timing and pattern of the cycle, for example requiring that the process be performed continuously for 1.28 seconds, or repeating the process sixteen times every 1.28 seconds. Further, certain Bluetooth specifications may require that the Bluetooth wakeup process be repeated, for example, at least once every 1.28 seconds, every 2.56 seconds, or any other interval which a particular specification may require.
While the phone's Bluetooth component scans for other Bluetooth-enabled devices as discussed above, the phone's CDMA component performs CDMA related tasks. Since CDMA requires precise time synchronization between the phone and the base station, one task the CDMA component has to perform is to synchronize with the base station. In order to synchronize with the base station while in idle mode, the CDMA component “wakes up” periodically during its allotted time slots to receive and process pilot signals from the base station on the CDMA Paging Channel. The CDMA component can synchronize with the base station by processing the pilot signals. For instance, the system time can be determined from the information embedded in the pilot signals.
How frequently the CDMA component wakes up is governed by the slot cycle index, which can be set by either the phone or the base station, as is known in the art. If the slot cycle index is zero, the CDMA component performs a wakeup process every 1.28 seconds, i.e. its allotted time slot comes around every 1.28 seconds. Alternatively, the slot cycle index can be set at, for example, one, in which case the wakeup process is performed every 2.56 seconds, or two, in which case the wakeup process is performed every 5.12 seconds. Thus, the lower the slot cycle index, the more frequently the wakeup process is repeated and the greater the power consumed.
Whether it is the Bluetooth component waking up and scanning for other Bluetooth-enabled devices and then shutting down, or the CDMA component waking up and synchronizing with the base station and then shutting down, power is consumed. Further, because each of the processes is performed repeatedly, the amount of power consumed can quickly drain the phone's power supply. Wasteful or excessive power consumption is of particular concern in wireless devices since it can hinder the device's operation and detract from its usefulness.
There is therefore a need in the art for a method and related system to reduce the amount of power consumed by various components of a Bluetooth enabled device, such as a Bluetooth-enabled CDMA cell phone.